1. Technical Field of the Invention
This invention relates to the preparation of polyamides from polyetheramines, hexamethylene diamine and adipic acid and more particularly it relates to altering the structure of nylon-6,6 to form an elastomeric nylon-6,6 based polymer by the introduction of higher molecular weight polyetheramines into nylon-6,6 polymers over a wide concentration range in order to improve impact resistance. In particular, this invention deals with overcoming compatibility problems inherent in adding high molecular weight polyetheramines into nylon-6,6.
2. Related Art
Ever since the development of nylon-6,6 by DuPont in the late 30's, there have been attempts to modify these polymers. An early patent (U.S. Pat. No. 2,359,867) describes the substitution of a portion of the hexamethyl diamine with triethylene glycol diamine.
In British Patent 562,370, Jun. 29, 1944 to I.C.I. polytriethylene glycol adipamide was mixed with hexamethylene adipimide to prepare modified nylon-6,6. The purpose of these modifications was to improve the moisture absorption properties of the polymer and the wearing comfort of the fabric and to increase the uses for nylon-6,6.
Other modifications of the nylon-6,6 molecule include the preparation of filaments with high elasticity and polymers with improved impact resistance and elasticity. U.S. Pat. No. 3,044,987 to DuPont (Jul. 17, 1962) describes the introduction of a polyether into the preparation of high molecular weight polyesteramides. ##STR1##
In U.S. Pat. No 3,454,534, there is claimed the addition of a polyether having a molecular weight of at least 1000 of the formula: NH.sub.2 (CH.sub.2).sub.3 -O-(RO).sub.x -(CH.sub.2).sub.3 -NH.sub.2 into the nylon-6,6 molecule. The concentration of the polyethers was 0.3 to 3% and R contained 2 to 8 carbon atoms.
There is disclosed in U.S. Pat. No. 4,044,071 a process for forming a blocked polyamide copolymer which comprises mixing a molten melt spinnable polyamide and a dry salt selected from the group consisting of specified prepolyamides and heating and mixing the mixture until substantially all of the salt and the polyamide are converted. Related U.S. Pat. No. 4,045,511 discloses a similar process for forming a block polyamide copolymer which involves dry blending a prepolyamide and particles of a melt-spinnable polyamide.
The invention of U.S. Pat. No. 4,113,794 is a normal copolymer formed by melt blending a melt spinnable polyamide, such as nylon-6,6 and a block of random poly(dioxa-amide). The block is derived from a copolymer prepared from a mixture of caprolactam, the salt of adipic acid and 4,7-dioxadecamethylene diamine. The resulting fiber has moisture absorption characteristics similar to that of cotton.
In U.S. Pat. No. 4,130,602 to Thompson et al., there is a disclosure of a novel block copolymer consisting of a specified polyamide and a specified poly(dioxamide) wherein it is noted that the incorporation of the poly(dioxa-amide) into polyamide does not adversely affect the desirable properties of the polyamide. Another patent to Thompson, U.S. Pat. No. 4,136,133, discloses a novel composition which is a block copolymer of a polyamide comprising a melt spinnable polyamide having no ether linkages. The fiber has the desirable properties of the major constituent, nylon-6,6, but also has superior absorption properties.
In U.S. Pat. No. 4,217,324 to Meeks, there is disclosed a method of making an antifriction nylon member comprising providing molten nylon monomers in two containers and mixing a liquid lubricant and a surfactant in the second container to form a homogeneous mixture, blending the mixture of the second container with that of the first to effect polymerization and defining a blend wherein said lubricant is substantially uniformly dispersed throughout the resulting molten nylon.
Impact resistant thermoplastic polyamides which are especially well suited for use as hot melt adhesives are disclosed in U.S. Pat. No. 4,320,213. They include polyamide forming moieties and polyamide forming oligomer moieties. In this patent, there is disclosed a composition comprising the product of melt-blending a polyamide resin, a hydroxyl-functional elastomer and a succinic-functional coupling agent, wherein the coupling agent provides effective coupling of the elastomer to the polyamide. This polyamide molding resin is suitable for molding into high impact resistant forms.
The invention of U.S. Pat. No, 4,374,741 is a novel lubricant for use in forming a stable, lubricating aqueous functional fluid which comprises a polyoxyalkylene polyamide lubricant having a terminal carboxylic acid group and a terminal amine group in the same molecule. It is useful in metal working and hydraulic fluids.
The object of U.S. Pat. No. 4,713,437 is to provide salts of dicarboxylic acids and oxyalkylenediamines which better satisfy the set requirements with regard to their characteristics. In particular, the periodate number and UV number of the salts after heat treatment along with other characteristics make it possible to produce nylons of improved quality. These compositions comprise a salt of an oxyalkylendiamine, an alkane-dicarboxylic acid and hydrazine.
In U.S. Pat. No. 4,868,280, there is disclosed a novel grade of copolyimides or tetramethylene adipamide (nylon 4,6) and tetramethylene terephthalamide (nylon 4,T) containing a mole fraction of nylon 4,T of 0.1 to 0.6 and having such a degree of orientation that the melting temperature shows little dependance on the composition of the copolyamide and remains relatively low. The copolyamides have good mechanical properties.
U.S. Pat. No. 3,044,987 is directed toward the attempt to introduce a polyether into a high molecular weight polyamide. Most of the related art deals with modifications to polyamides other than nylon-6,6 and to difficulties encountered with modifications.
In an article entitled "Segmented block Copolymers based on polyamide-4,6 and poly(propylene oxide)" by van Hutton, et al., Polymer, 1990, Vol. 31, March, p. 524, there is a discussion of work performed by the authors wherein they allowed Jeffamine amines to react with adipic acid in the presence of nylon-4,6 salt. This reaction can be represented by the equation: ##STR2##
One disadvantage of the work by van Hutton et al. is the lack of control over the amount of propylene oxide mixed into the polymer.
It would be very advantageous if a method were available which reduced the difficulties inherent in introducing a polyether into nylon-6,6 in particular. In addition, it would be advantageous to those skilled in the art if the amount of polyether could be varied. A process which facilitated the production of a homogeneous copolymer would be very desirable in the art.
In addition, if such a process resulted in novel nylon-6,6 based polymers having modified structures which incorporated polyoxypropylene diamines, polybutylene glycol diamines, aminopropyl polytetramethylene glycol diamines and polytetramethylene glycol diamines, and these polymers exhibited improved impact resistance, the usefulness of such modifications would be obvious to those skilled in the art.
It is the purpose of the instant work to describe the preparation of nylon-6,6 polyamides which have been modified by a high percentage of hydrophobic polyethers. The types of polyethers claimed are described as follows: ##STR3## where x has a value of greater than 2 and less than 30.
Since these polyether diamines have a reactivity that is different from hexamethylene diamine the homogeneous copolymers of the invention are prepared by first preparing the adipic acid amide of the polyetheramine.